The present invention relates to infusion systems, and particularly to a drop monitoring unit for monitoring drop formation and/or volume of infusion in an infusion set.
A wide number of drop monitoring units have been developed for infusion sets, as described for example in U.S. Pat. Nos. 4,018,362, 4,038,982, 4,314,484, 4,328,801, Re 32,294 of U.S. Pat. No. 4,397,648, 4,469,480, 4,496,351, 4,498,901, 4,533,350, 4,775,368, 5,152,424 and 5,267,978. The known devices, however, generally are incorporated into the construction of the drip chamber or require a specific construction of a drip chamber, and therefore are not capable of being applied as add-on units to existing infusion sets. Other known constructions are relatively complicated and therefore expensive to produce.